Medical grafting methods

ABSTRACT

Methods and apparatus for delivering and installing a new Length of tubing between two sections of a patient&#39;s existing body organ tubing and at least partly outside of that existing structure. For example, the new length of tubing may be for the purpose of providing the patient with a coronary bypass. The new tubing may be an artificial graft, a natural graft (harvested elsewhere from the patient), or both. The new tubing is delivered to and installed at the operative site primarily by working through the patient&#39;s existing tubular body organ structure. This avoids the need for any significant surgery on the patient. The artificial grafts may have shapes other than tubular. Certain procedural and apparatus aspects of the invention have uses other than in connection with grafting in general or tubular grafting in particular.

BACKGROUND OF THE INVENTION

This invention relates to grafts for use in the repair, replacement, orsupplement of a medical patient's natural body organ structures ortissues. The invention also relates to methods for making graftstructures. The invention further relates to methods and apparatus fordelivering a graft to an operative site in a patient, and for installingthe graft at that site. Some aspects of the invention may have otheruses such as for viewing the interior of a patient, providing access tothe interior of a patient for other procedures, etc. An example of thepossible uses of the invention is a minimally invasive cardiac bypassprocedure. This example will be considered in detail, but it will beunderstood that various aspects of the invention have many otherpossible uses.

Several procedures are known for revascularizing the human heart inorder to treat a patient with one or more occluded coronary arteries.The earliest of these procedures to be developed involves exposing theheart by means of a midline sternotomy. Following surgical exposure ofthe heart, the patient's aorta and vena cava are connected to aheart/lung machine to sustain vital functions during the procedure. Thebeating of the heart is stopped to facilitate performance of theprocedure. Typically, a suitable blood vessel such as a length of thepatient's saphenous (leg) vein is harvested for use as a graft. Thegraft is used to create a new, uninterrupted channel between a bloodsource, such as the aorta, and the occluded coronary artery or arteriesdownstream from the arterial occlusion or occlusions.

A variation of the above procedure involves relocating a mammary arteryof the patient to a coronary artery.

Although the above-described sternotomy procedures are increasinglysuccessful, the high degree of invasiveness of these procedures and therequirement of these procedures for general anesthesia are significantdisadvantages. Indeed, these disadvantages preclude use of s3ternotomyprocedures on many patients.

More recently, less invasive procedures have been developed forrevascularizing the heart. An example of these procedures is known asthoracostomy, which involves surgical creation of ports in the patient'schest to obtain access to the thoracic cavity. Specially designedinstruments are inserted through the port, to allow the surgeon torevascularize the heart withou the trauma of a midline sternotomy. Drugsmay be administered to the patient to slow the heart during theprocedure. Some thoracostomy procedures involve relocating a mammaryartery to a coronary artery to provide a bypass around an occlusion inthe coronary artery.

Thoracostomy bypass procedures are less traumatic than sternotomy bypassprocedures, but they are still too traumatic for some patients. Also,the number of required bypasses may exceed the number of mammaryarteries, thereby rendering thoracostomy procedures inadequate to fullytreat many patients.

Another technique for revascularizing the human heart involves gainingaccess to the thoracic cavity by making incisions between the patient'sribs. This procedure is known as thoracotomy. It is also substantiallyless traumatic than midline sternotomy, but it is still too traumaticfor some patients.

In view of the foregoing, it is an object of this invention to provideless traumatic methods and apparatus for revascularizing a patient.

It is another object of the invention to provide minimally invasivemethods and apparatus for repairing, replazing, or supplementing theblood vessels or other body organ tubing or tissues of a patient.

It is still another object of the invention to provide improved graftstructures for use in the repair, replacement, or supplementing ofnatural body organ structures or tissues, and to provide methods formaking such graft structures.

It is yet another object of the invention to provide improved methodsand apparatus for transporting or delivering and installing graftstructures for use in the repair, replacement, or supplementing ofnatural body organ structures or tissues of a patient.

SUMMARY OF THE INVENTION

These and other objects of the invention are accomplished in accordancewith the principles of the invention by providing methods and apparatusfor substantially non-surgically installing a new length of tubing in apatient between two sections of the patient's existing body organtubing, the new length of tubing being delivered to the operative siteby passing along existing tubing, but installed at the operative site sothat it is at least partly outside the existing tubing. (As used herein,references to a patient's existing body organ tubing or the like includeboth natural and previously installed graft tubing (whether natural,artificial, or both). A previous installation of graft tubing may haveoccurred in a previous procedure or earlier in a current and on-goingprocedure. References to a length of tubing also include plural lengthsof tubing.) At one end of the operative site, the new length of tubingis caused to extend out through an opening made in the existing tubing.The outwardly extending end portion of the new tubing is guided to theother end of the operative site. At that other end another opening ismade in the existing tubing and the extending end portion of the newtubing is attached to the existing tubing via that opening. The otherend portion of the new tubing (remote from the extending portion) issimilarly attached to the existing tubing at the first-describedopening. The new tubing installation is now complete, and the apparatusused to make the installation can be withdrawn from the patient.

In the most preferred embodiment, all or substantially all necessaryapparatus is inserted into the patient via the patient's existing bodyorgan tubing. In addition, all or substantially all apparatus functionsat the operative site are remotely controlled by the physician (a termused herein to also include supporting technicians) from outside thepatient's body.

Preferred apparatus in accordance with the invention includes a firstelongated instrument for extending through the patient's existing bodyorgan tubing to a first end of the operative site, and a secondelongated instrument for similarly extending through the patient'sexisting tubing to a second end of the operative site. Each instrumentincludes a structure capable of penetrating the existing tubing at theassociated end of the operative site. In addition, these structures arecapable of interengaging with one another outside he existing tubing toprovide a substantially continuous structural path from outside thepatient, along the patient's existing tubing, and then outside thattubing from one end to the other of the operative site. This structureis used to guide the new length of tubing into the patient and intoposition at the operative site.

At least one of the elongated instruments preferably includes mechanismsfor fastening each end portion of the new length of tubing to theadjacent existing body organ tubing. For example, these mechanisms mayactivate fasteners on or associated with the new tubing.

The new tubing may be artificial graft tubing. Alternatively, the newtubing may be natural body organ tubing (e.g., tubing harvested fromanother location in the patient's body). As still another alternative,the new tubing may be a combination of artificial and natural tubing(e.g., natural tubing disposed substantially concentrically insideartificial tubing).

A preferred form of artificial tubing includes a tube frame of a firsthighly elastic material (such as nitinol) covered with a second highlyelastic material (such as silicone rubber) to substantially fill in theapertures in the frame. This combination produces an artificial graftthat is distensible like natural body organ tubing such as a naturalartery. The covering on the frame is preferably made porous to apredetermined degree to improve its bio-utility in this context. Apreferred method of providing such porosity is to make the covering froman elastic material that is mixed with particles of a material that canbe removed (e.g., by vaporization) after the covering has been appliedto the mesh. When the particles are removed, voids are left in thecovering that give it the desired porosity.

The artificial grafts of this invention may be coated (in the case oftubular grafts, on the inside and/or outside) to still further enhancetheir bio-utility. Examples of suitable coatings are medicated coatings,hydrophylic coatings, smoothing coatings, collagen coatings, human cellseeding coatings, etc. The above-described preferred porosity of thegraft covering helps the graft to retain these coatings. Additionaladvantages of the artificial grafts of this invention are theirelasticity and distensibility (mentioned above), their ability to bedeployed through tubes of smaller diameter (after which theyautomatically return to their full diameter), the possibility of makingthem modular, their ability to accept natural body organ tubingconcentrically inside themselves, their ability to support developmentof an endothelial layer, their compatibility with MRI procedures, theirability to be made fluoroscopically visible, etc.

Although grafts in the form of tubing are described above, certainaspects of the invention are equally applicable to other graftprocedures and to grafts having other shapes.

Further features of the invention, its nature and various advantageswill be more apparent from the accompanying drawings and the followingdetailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified longitudinal sectional view showing a portion ofan illustrative procedure and related apparatus in accordance with thisinvention.

FIG. 2 is a simplified longitudinal sectional view showing a portion ofa more particular illustrative procedure and related apparatus inaccordance with the invention.

FIG. 3 is a simplified longitudinal sectional view showing anillustrative embodiment of a portion of the FIG. 2 apparatus in moredetail.

FIG. 3a is a view similar to FIG. 3 showing an alternative illustrativeembodiment of the FIG. 3 apparatus.

FIG. 4 is a simplified elevational view showing an illustrativeembodiment of a portion of the FIG. 3 apparatus in still more detail.

FIG. 5 is a simplified longitudinal sectional view showing anotherportion of an illustrative procedure and related apparatus in accordancewith this invention.

FIG. 6 is a view similar to FIG. 2 showing a later stage in theillustrative procedure depicted in part by FIG. 2, together with relatedapparatus, all in accordance with this invention.

FIG. 7a is a simplified longitudinal sectional view of an illustrativeembodiment of a portion of the FIG. 6 apparatus in more detail.

FIG. 7b is a simplified elevational view of a portion of the FIG. 7aapparatus, but with the depicted elements in a different physicalrelationship to one another.

FIG. 7c is a simplified longitudinal sectional view of an alternativeembodiment of one component of the FIG. 7a apparatus.

FIG. 7d is a simplified longitudinal sectional view of an alternativeembodiment of another component of the FIG. 7a apparatus.

FIG. 7e is a simplified elevational view of another alternativeembodiment of the component shown in FIG. 7d.

FIG. 7f is a simplified elevational view of an alternative embodiment ofstill another component shown in FIG. 7a.

FIG. 7g is a simplified elevational view of an alternative embodiment ofyet another component shown in FIG. 7a.

FIG. 8 is a simplified longitudinal sectional view similar to a portionof FIG. 6 showing a still later stage in the illustrative proceduredepicted in part by FIG. 6.

FIG. 8a is a simplified sectional view of the apparatus shown in FIG. 8without the associated tissue structure being present.

FIG. 9 is a simplified cross sectional view of an illustrativeembodiment of further illustrative apparatus in accordance with thisinvention.

FIG. 10 is a simplified longitudinal sectional view of an illustrativeembodiment of a portion of the FIG. 9 apparatus.

FIG. 10a is a view similar to FIG. 10 showing a possible alternativeconstruction of the FIG. 10 apparatus.

FIG. 10b is another view similar to FIG. 10 showing another possiblealternative construction of the FIG. 10 apparatus.

FIG. 10c is another view similar to FIG. 10 showing still anotherpossible alternative construction of the FIG. 10 apparatus.

FIG. 11 is a view similar to FIG. 6 showing an even later stage in theillustrative procedure depicted in part by FIG. 8, together with relatedapparatus, all in accordance with this invention.

FIG. 12 is a view similar to a portion of FIG. 11, but in somewhat moredetail, showing a still later stage in the illustrative proceduredepicted in part by FIG. 11.

FIG. 12a is a view similar to FIG. 12 showing a possible alternativeconstruction of the FIG. 12 apparatus.

FIG. 13 is a view similar to FIG. 12 showing an even later stage in theillustrative procedure depicted in part by FIG. 12.

FIG. 14 is a view similar to FIG. 11 showing a still later stage in theillustrative procedure depicted in part by FIG. 13.

FIG. l5 is a simplified longitudinal sectional view of an illustrativeembodiment of a portion of still further illustrative apparatus inaccordance with this invention.

FIG. 15a is a simplified elevational view of a structure which can beused to provide part of the apparatus shown in FIG. 15.

FIG. 15b is a view similar to FIG. 15a showing more of the structure ofwhich FIG. 15a is a part.

FIG. 15c is a view similar to FIG. 15b showing the FIG. 15b structure inanother operational condition.

FIG. 15d is a simplified elevational view of an alternative structurewhich can be used to provide part of apparatus shown in FIG. 15.

FIG. 15e is a view similar to FIG. 15d showing the FIG. 15d structure inanother operational condition.

FIG. 15f is a simplified longitudinal sectional view of anotheralternative structure which can be used to provide part of the apparatusshown in FIG. 15.

FIG. 15g is a view similar to FIG. 15f showing the FIG. 15f structure inanother operational condition.

FIG. 16 is a simplified elevational view of an illustrative embodimentof one component of the FIG. 15 apparatus.

FIG. 17 is a simplified longitudinal sectional view of an illustrativeembodiment of another portion of the FIG. 15 apparatus.

FIG. 18 is a view similar to a portion of FIG. 14 showing an even laterstage in the illustrative procedure depicted in part by FIG. 14.

FIG. 19 is a view similar to FIG. 18 showing a still later stage in theFIG. 18 procedure.

FIG. 20 is a view similar to FIG. 19 showing an even later stage in theFIG. 19 procedure.

FIG. 21 is a view similar to another portion of FIG. 14 showing a stilllater stage in the FIG. 20 procedure.

FIG. 22 is a view similar to FIG. 21 showing an even later stage in theFIG. 21 procedure.

FIG. 22a is a view similar to FIG. 22 showing a still later stage in theFIG. 22 procedure.

FIG. 22b is a view similar to FIG. 22a showing an even later stage inthe FIG. 22a procedure.

FIG. 23 is a view similar to FIG. 22b showing a still later stage in theFIG. 22b procedure.

FIG. 24 is a view similar to FIG. 23 showing an even later stage in theFIG. 23 procedure.

FIG. 25 is a simplified longitudinal sectional view of an illustrativeembodiment of a portion of more apparatus in accordance with thisinvention.

FIG. 26 is a view similar to FIG. 20 showing a later stage in the FIG.24 procedure.

FIG. 27 is a view similar to FIG. 26 showing a still later stage in theFIG. 26 procedure.

FIG. 28 is a view similar to FIG. 24 showing an even later stage in theFIG. 27 procedure.

FIG. 29 is a view similar to FIG. 28 showing a still later stage in theFIG. 28 procedure.

FIG. 30 is a view similar to FIG. 29 showing an even later stage in theFIG. 29 procedure.

FIG. 31 is a view similar to FIG. 14 showing the end result of theprocedure depicted in part by FIG. 30.

FIG. 32 is a simplified longitudinal sectional view showing an endresult similar to FIG. 31 but in a different context.

FIG. 33 is a simplified longitudinal sectional view showing a possiblealternative construction of portions of the apparatus showing in FIG.15.

FIG. 34 is a simplified elevational view (partly in section) showinganother possible alternative construction of portions of the FIG. 15apparatus.

FIG. 35 is a simplified longitudinal sectional view of the FIG. 34apparatus in another operating condition.

FIG. 36 is a simplified elevational view of apparatus which can be usedas an alternative to certain apparatus components shown in FIGS. 15 and17.

FIG. 37 is a simplified elevational view (partly in section) showingadditional components with the FIG. 36 apparatus.

FIG. 38 is a simplified longitudinal sectional view showing stillanother possible alternative construction of portions of the FIG. 15apparatus.

FIG. 39 is a simplified elevational view showing in more cetail apossible construction of a portion of the FIG. 38 apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Because the present invention has a number of different applications,each of which may warrant some modifications of such parameters asinstrument size and shape, it is believed best to describe certainaspects of the invention with reference to relatively generic schematicdrawings. To keep the discussion from becoming too abstract, however,and as an aid to better comprehension and appreciation of the invention,references will frequently be made to specific uses of the invention.Most often these references will be to use of the invention to provide abypass around an occlusion or obstruction (generically referred to as anarrowing) in a patient's coronary artery, and in particular a bypassfrom the aorta to a point along the coronary artery which is downstreamfrom the coronary artery narrowing. It is emphasized again, however,that this is only one of many possible applications of the invention.

Assuming that the invention is to be used to provide a bypass from theaorta around a coronary artery narrowing, the procedure may begin byinserting an elongated instrument into the patient's circulatory systemso that a distal portion of the instrument extends through the coronaryartery narrowing to the vicinity of the point along the artery at whichit is desired to make the bypass connection. This is illustrated by FIG.1 which shows elongated instrument 100 entering the patient'scirculatory system 10 at a remote location 12 and passing coaxiallyalong vessels in the circulatory system until its distal end portion 104passes through narrowing 22 in coronary artery 20 and reaches thedownstream portion 24 of the artery to which it is desired to make abypass connection. For example, the entry location 12 of irnstrument 100may be a femoral (leg) artery of the patient, a brachial artery of thepatient, or any other suitable entry point. It will be appreciated,however, that entry point 12 is typically remote from the location atwhich the bypass is to be provided, and that control of instrument 100throughout its use is from the proximal portion 102 that is outside thepatient at all times.

For the illustrative procedure being discussed, FIG. 2 shows a preferredembodiment of instrument 100 in more detail. As shown in FIG. 2,instrument 100 may include a catheter tube 110 which is inserted (fromlocation 12 in FIG. 1) via the patient's aorta 30 to the ostium ofcoronary artery 20. Another tubular structure 120 is then extended fromthe distal end of catheter 110, through narrowing 22 to location 24.

An illustrative construction of tubular structure 120 is shown in moredetail in FIG. 3. There it will be seen that structure 120 may have twolumens 130 and 140. Near the distal end of structure 120, lumen 130communicates with the interior of an inflatable balloon 132 on one sideof structure 120, while lumen 140 opens out to the opposite side ofstructure 120. Lumen 140 contains a longitudinal structure 150 which maybe a stylet wire with a sharpened distal tip 152 (see FIG. 4). (AlthoughFIG. 4 shows indentations behind tip 152, those indentations could beeliminated if desired.) Structure 120 may be provided with a distalspring tip 122 to help guide the distal end of structure 120 alongcoronary artery 20 and through narrowing 22. A safety ribbon 123 (e.g.,of the same material as tip 122) may be connected at its proximal end tothe distal end of member 120 and at its distal end to the distal end oftip 122 to improve the performance of tip 122 and to help preventseparation of any portion of tip 122 from structure 120 in the event ofdamage to tip 122. Structure 120 may have radiologic (e.g., radio-opaqueor fluoroscopically viewable) markers 124 at suitable locations to helpthe physician place the structure where desired in the patient's body.Catheter 110 may also have radiologic markers 112 for similar use.Balloon 132 is initially deflated. Longitudinal structure 150 isinitially retracted within lumen 140. However, the distal portion oflumen 140 is shaped (as indicated at 142 in FIG. 2) to help guide thedistal tip 152 of structure 150 out to the side of structure 120 whenstructure 150 is pushed distally relative to structure 120. This isdiscussed in more detail below. As earlier description suggests, each ofcomponents 110, 120, and 150 is separately controllable from outside thepatient, generally indicated as region 102 in FIG. 1.

As an alternative to providing balloon 132 as an integral part of onestructure 120, balloon 132 may be provided on another longitudinalstructure 120' (FIG. 3a) which is substantially parallel to theremaining components described above for structure 120. Structure 120'may be substantially separate from structure 120, or it may be attachedto structure 120.

After instrument 100 is positioned as shown in FIGS. 1 and 2, a secondelongated instrument 200 is similarly introduced into the patient'scirculatory system 10 as shown generally in FIG. 5. For example,instrument 200 may enter the patient (at 14) via a femoral artery, abrachial artery, or any other suitable location, which again istypically remote from the bypass site. If one femoral artery is used toreceive instrument 100, the other femoral artery may be used to receiveinstrument 200. Or the same femoral artery may be used to receive bothinstruments. Or any other combination of entry points may be used forthe two instruments. Instrument 200 is inserted until its distal end isadjacent to the point 34 in the circulatory system which it is desiredto connect to point 24 via a bypass. This is illustrated in a morespecific example in FIG. 6 where the distal end of instrument 200 isshown at location 34 in aorta 30. The particular location 34 chosen inFIG. 6 is only illustrative, and any other location along aorta 30 maybe selected instead. Radiologic markers 206 may be provided on thedistal portion of instrument 200 to help the physician position theinstrument where desired. Note that FIG. 6 shows portions of instruments100 and 200 side by side in aorta 30.

An illustrative construction of instrument 200 is shown in more detailin FIG. 7a. This FIG. shows the distal portions of elements 220, 230,240, and 250 telescoped out from one another and from the distal end ofouter member 210 for greater clarity. It will be understood, however,that all of these elements are initially inside of one another andinside outer member 210. Indeed, member 210 may be initially positionedin the patient without any or all of elements 220, 230, 240, and 250inside, and these elements may then be inserted into member 210.Moreover, the number of members like 220, 230, etc., may be more or lessthan the number shown in FIG. 7a, depending on the requirements of aparticular procedure.

Outer member 210 may be a catheter-type member. The distal portion ofcatheter 210 may carry two axially spaced annular balloons 212 and 214.Proximal balloon 212 is inflatable and deflatable via inflation lumen216 in catheter 210. Distal balloon 214 is inflatable and deflatable viainflation lumen 218 in catheter 210. Lumens 216 and 218 are separatefrom once another so that balloons 212 and 214 can be separatelycontrolled. Balloons 212 and 214 are shown substantially deflated inFIG. 7a. The distal end of catheter 210 may be tapered as shown at 211in FIG. 7c to facilitate passage of catheter 210 through an aperture inaorta 30 as will be described below.

Coaxially inside catheter 210 is tubular sheath member 220. Sheath 220is longitudinally movable relative to catheter 210. The distal portionof sheath 220 may be tapered as shown at 222 in FIG. 7d, and/orexternally threaded as shown at 224 in FIG. 7e. Either or both offeatures 222 and 224 may be provided to facilitate passage of sheath 220through an aperture in aorta 30 as will be described below. If threads224 are provided, then sheath 220 is rotatable (either alone or withother components) about the longitudinal axis of instrument 200 in orderto enable threads 224 to engage the tissue of the aorta wall and helppull sheath 220 through the aorta wall.

Coaxially inside sheath member 220 is power steering tube 230. Tube 230is longitudinally movable relative to sheath 220. Tube 230 may also berotatable (about the central longitudinal axis of instrument 200)relative to sheath 220, and the distal end of tube 230 may be threadedon the outside (as shown at 232 in FIG. 7f) for reasons similar to thosefor which threading 224 may be provided on sheath 220. Tube 230 ispreferably controllable from its proximal portion (outside the patient)to deflect laterally by a desired amount to help steer, push, or twistinstrument 200 to the desired location in the patient.

Coaxially inside tube 230 is tube 240. Tube 240 is longitudinallymovable relative to tube 230, and may be metal (e.g., stainless steel)hypotube, for example. Screw head 242 is mounted on the distal end oftube 240 and is threaded (as indicated at 244) on its distal conicalsurface. Tube 240 is rotatable (about the central longitudinal axis ofinstrument 200, either alone or with other elements) in order rotatehead 242 and thereby use threads 244 in engagement with the tissue ofthe aorta wall to help pull head 242 through that wall as will be morefully described below. Because tube 240 is hollow, it can he used forpassage of fluid or pressure into or out of the patient.

Coaxially inside tube 240 is longitudinal structure 250. Longitudinalstructure 250 is longitudinally movable relative to tube 240. Structure250 may also be rotatable (about its longitudinal axis) relative to tube240 and/or other elements. Structure 250 may be a wire with a distal endportion 252 that is resiliently biased to deflect laterally to one side.Wire portion 252 is kept relatively straight when it is inside tube 240as shown in FIG. 7a. But when wire portion 252 is pushed axially out thedistal end of tube 240, it curves to one side as shown in FIG. 7b. As analternative or addition to the above-described resilient lateraldeflection, the distal portion of structure 250 may be threaded as shownat 254 in FIG. 7g to help structure 250 thread its way through the wallof aorta 30.

All of components 210, 220, 230, 240, and 250 are controlled fromoutside the patient's body (i.e., from region 202 in FIG. 5).

When the distal portion of catheter 210 is at the desired location 34,proximal balloon 212 is inflated. Even when inflated, proximal balloon212 is not large enough to block aorta 30.

After proximal balloon 212 has been inflated, wire 250 is pusheddistally so that its distal portion emerges from the distal end of tube240 and penetrates the wall of aorta 30 at location 34. This anchors thedistal portion of instrument 200 to the aorta wall at the desiredlocation. Because of its operation to thus anchor instrument 200, wire250 is sometimes referred to as an anchor wire. The rotatability of wire250, as well as its resilient lateral deflection (FIG. 7b) and/orthreads 254 (FIG. 7g), may be used to help get the distal end of thewire to the desired location 34 and firmly into the aorta wall at thatlocation in order to achieve the desired anchoring of instrument 200.

When instrument 200 is sufficiently anchored by wire 250, tubes 230 and240 are moved in the distal direction relative to wire 250 so that screwhead 242 begins to follow wire 250 into and through the aorta wall.During this motion, at least tube 240 is rotated about its longitudinalaxis so that threads 244 help to pull head 242 into and through theaorta wall. The distal portion of tube 230 follows head 242 through theaorta wall. If provided, threads 232 and rotation of tube 230 mayfacilitate transfer of the aorta wall tissue from head 242 to tube 230.

When tube 230 is through the aorta wall, sheath 220 is moved distallyrelative to tube 230 so that a distal portion of sheath 220 follows tube230 through the aorta wall. If provided, the distal taper 222 and/orthreads 224 and rotation of sheath 220 help the distal portion of sheath220 through the aorta wall. Then catheter 210 is advanced distallyrelative to sheath 220 so that a distal portion of catheter 210 followssheath 220 through the aorta wall. Again, the distal taper 211 ofcatheter 210 (if provided) helps the distal portior of the catheterthrough the aorta wall. Inflated proximal balloon 212 prevents more thanjust the portion of catheter 210 that is distal of balloon 212 frontpassing through the aorta wall.

It should be mentioned that each time another, larger one of elements240, 230, 220, and 210 is pushed through the aorta wall, the previouslyextended elements can be and preferably are either held stationary orpulled back proximally to prevent them from damaging body tissuesoutside the aorta.

When the distal portion of catheter 210 is through the aorta wall,distal balloon 214, which is now outside the aorta, is also inflated.The axial spacing between balloons 212 and 214 is preferably smallenough so that the aorta wall is clamped between these two balloons asshown in FIG. 8. For example, if balloons 212 and 214 were inflatedwithout the presence of the aorta wall, their appearance might be asshown in FIG. 8a. The close spacing of balloons 212 and 214, as well astheir resilient bias toward one another, helps to anchor catheter 210through the aorta wall and also to seal the aorta wall around thecatheter. Balloons 212 and 214 may be inflated by liquid or gas, andthey may be specially coated to help improve the seal between catheter210 and the aorta wall.

After the condition of catheter 210 shown in FIG. 8 has been reached,all of components 220, 230, 240, and 250 can be withdrawn from thepatient by pulling them out of catheter 210 in the proximal direction.

The next step in the illustrative procedure being described is to insertan elongated, steerable, endoscopic snare 300 lengthwise into catheter210. A simplified cross sectional view of an illustrative steerableendoscopic snare is shown in FIG. 9. As shown in that FIG., snare 300includes one or more sheath structures such as 310a and 310b that areoperable by the physician to steer the snare by curvilinearly deflectingit laterally by a desired, variable amount. Within sheaths 310 are suchother components as (1) a fiber optic bundle 320 for conveying lightfrom outside the patient to the distal end of snare 300 in order toprovide illumination beyond the distal end of the snare, (2) anotherfiber optic bundle 330 for conveying an image from beyond the distal endof the snare back to optical and/or video equipment outside the patientand usable by the physician to see what is beyond the distal end of thesnare, and (3) a snare sheath 340 with the actual snare instrument 350inside of it. Additional lumens such as 360 may be provided for suchpurposes as introducing fluid that may help to clear the distal ends offiber optic bundles 320 and 330, for introducing fluid for irrigatingand/or medicating the patient, for suctioning fluid from the patient,etc. It may not be necessary to provide a separate snare sheath 340, butrather element 340 may merely be a lumen through the general structure300 for snare instrument 350.

An illustrative embodiment of the distal portion of snare instrument 350is shown in FIG. 10. In this embodiment instrument 350 includes a wire352 with a snare loop 354 (also of wire) at its distal end. Loop 354 isclosed when it is inside snare sheath or lumen 340. Loop 354 opensresiliently to the shape shown in FIG. 10 when it extends distallybeyond the distal end of sheath or lumen 340.

In the alternative embodiment of instrument 350 shown in FIG. 10a, snareloop 354 is mounted on the distal end of a fiber optic bundle 352'.Fiber optic bundle 352' may perform the functions described above forbundle 320 or bundle 330, thereby integrating those functions intoinstrument portion 350.

In the further alternative embodiment of instrument 350 shown in FIG.10b, snare loop 354 is mounted on the distal end of a tube 352", whichcan be used to deliver other types of instrumentation to the vicinity ofsnare loop 354. For example, tube 352" may be metal (e.g., stainlesssteel) hypotube, and the other instrumentation delivered via that tubemay be a tissue cutter for use in cooperation with snare loop 354 toperform a biopsy.

In the still further alternative embodiment shown in FIG. 10c, snareloop 354 is part of one continuous length of wire 352a. A possibleadvantage of the embodiment shown in FIG. 10c is that it permits snareloop 354 to be variable in size, determined by how much of wire 352a isextended from the distal end of lumen 340.

As shown in FIG. 11, the distal portion of steerable endoscopic snare300 is extended distally beyond the distal end of catheter 210 andsteered by the physician until it is adjacent to the exterior ofcoronary artery portion 24.

The next step in the illustrative procedure being described ispreferably to deploy snare loop 354 by extending it distally from thedistal end of structure 300 as shown in FIG. 12. Alternatively, thisstep could be performed somewhat later.

The next step (also shown in FIG. 12) is to inflate balloon 132 to pushtube 120 against the opposite side wall of coronary artery 20 atlocation 24. Then stylet wire 150 is moved in the distal direction asshown in FIG. 12 so that its distal tip 152 passes through the wall ofthe coronary artery. As was mentioned earlier, the distal end of thestylet wire lumen in tube 120 is shaped to help guide stylet wire 150through the coronary artery wall. After stylet wire 150 is through thecoronary artery wall, balloon 132 can be deflated. Balloon 132 may be aperfusion balloon which allows continued blood flow along artery 20 evenwhile the balloon is inflated.

It may not be necessary to have a balloon 132 directly opposite theoutlet for wire 150. For example, FIG. 12a shows an alternativeembodiment in which a perfusion balloon 132' is provided on tube 120proximally of the outlet for wire 150. Balloon 132' is inflated when itis desired to stabilize the location of tube 120 in coronary artery 20(e.g., while the distal portion of wire 150 is being pushed out throughthe coronary artery wall). Another possibility is for a balloon like132' to be near the distal end of a balloon catheter from which tube 120extends distally. Still another possibility may be to omit balloons like132 and 132' entirely. If a balloon 132 or 132' is provided, it may notbe necessary for it to be a perfusion balloon.

When the distal portion of stylet wire 150 is outside coronary artery20, the next step is to ensure that the distal portion of the wirepasses through snare loop 354 as shown in FIG. 12 or FIG. 12a. This maybe facilitated by continued use of the visual observation and steeringcapabilities of snare 300. An especially preferred technique is todeploy snare loop 354 so that it is next to coronary artery section 24.Then when stylet wire 150 emerges from the coronary artery at 24, itimmediately passes through snare loop 354 with no further manipulationbeing required.

Once wire 150 is through snare loop 354, snare sheath or lumen 340 ismoved distally relative to the snare loop. This causes snare loop 354 toclose down on wire 150. Snare sheath or lumen 340 also tends to trap thedistal portion of wire 150 and to fold that wire portion back on itselfinside sheath or lumen 340 as shown in FIG. 13.

When the condition shown in FIG. 13 is achieved, longitudinal structures150 and 350 are securely interencgaged inside snare sheath or lumen 340.The next step is to pull wire 352 in the proximal direction all the wayout of the patient at location 202 (FIG. 5). Because of theinterengagement between wires 150 and 352, withdrawing wire 352 pulls asmuch additional wire 150 into the patient from external location 102(FIG. 1). When wire 352 has been completely removed from the patient,there is then one continuous wire 150 from outside the patient at 102,through the patient, to outside the patient at 202. Wire 150 can now bemoved in either longitudinal direction through the patient. This wire oranother wire could be used to help pull various apparatus into thepatient via the tube or tubes through which the wire passes.

After one continuous wire 150 has been established through the patientas described above, steerable endoscopic snare 300 may be withdrawn fromthe patient by pulling it proximally out of catheter 210. The conditionof the apparatus inside the patient is now as shown in FIG. 14. Notethat the resence of fixed outlets for the wire from the distal ortion oftube 120 and the distal end of catheter 210 prevents wire 150 fromcutting tissues 20 and 30 when the wire is pulled in either longitudinaldirection. The portion of whre 150 extending through the interior of thepatient between elements 120 and 210 may have radiologic markers 154equally spaced along its length. These can be viewed radiologically bythe physician to determine the distance between regions 24 and 34 viawire 150. This helps the physician select the correct length of graftneeded between regions 24 and 34.

The next phase of the illustrative procedure being described is toinstall a new length of tubing between regions 24 and 34. The new lengthof tubing may be either an artificial graft, natural body organ tubingharvested from the patient's body, or a combination of artificial andnatural tubing (e.g., natural tubing coaxially inside artificialtubing). In the following discussion it is assumed that the new tubingis to be natural tubing (e.g., a length of the patient's saphenous veinthat has been harvested for this purpose) inside an artificial conduit.When such a combination of natural and artificial conduits is used, bothconduits can be delivered and installed simultaneously, Dr the outerartificial conduit can be delivered and installed first, and then theinner natural conduit can be delivered and installed. The followingdiscussion initially assumes that the latter technique is employed.

In accordance with the above-stated assumptions, the next step in theprocedure is to use catheter 210 and wire 150 to deliver an artificialconduit so that it extends between regions 24 and 34. The distal portionof an illustrative assembly 400 for doing this is shown in FIG. 15.(Several alternative constructions of this portion of the apparatus areshown in later FIGS. and described below.)

As shown in FIG. 15 assembly 400 includes a threaded, conical, distaltip 412 mounted on a tubular member 410 (e.g., metal hypotube) throughwhich wire 150 can freely pass. Additional details regarding variouspossible constructions of tip 412 are provided later with reference toFIGS. 15a-15g, but it should be mentioned here that in this embodimenttip 412 is selectively collapsible to facilitate its withdrawal from thepatient after it has served its purpose. Another tubular member 420 isdisposed concentrically around tubular member 410. An inflatable balloon422 is mounted on the distal end of tubular member 420. Tubular member420 includes an axially extending lumen (not shown in FIS. 15) for usein selectively inflating and deflating balloon 422. Balloon 422 is showndeflated in FIG. 15.

Coaxially around tubular member 420 is an artificial graft conduit 430.An illustrative embodiment of a suitable conduit 430 is shown in FIG. 16and inclades a tube formed of a frame 432 of a first highly elasticmaterial (such as nitinol) with a covering 434 of a second highlyelastic material (e.g., a rubber-like material such as silicone)substantially filling the apertures in the frame. Additional informationregarding this possible embodiment of conduit 430 and Dther artificialgraft structures in accordance with the invention is provided in laterportions of this specification. Here it will suffice to say that thisstructure is extremely elastic, flexible, pliable, and resilient. Forexample, it can be stretched to a small fraction of its originaldiameter, and it thereafter returns by itself to its original size andshape without damage or permanent deformation of any kind. In addition,this structure is distensible so that it may pulsate very much likenatural circulatory system tubing in response to pressure waves in theblood flow. This helps keep the conduit open, especially if it is usedby itself as the final graft conduit. At its distal end, extensions offrame 432 are flared out to form resilient hooks or barbs 436, thepurpose of which will become apparent as the description proceeds. Nearthe proximal end of conduit 430 two axially spaced resilient flaps 438aand 438b with barbs 439 are provided. The purpose and operation ofelements 438 and 439 will also become apparent as the descriptionproceeds.

In assembly 400 (see again FIG. 15, and also FIG. 17), barbs 436 andflaps 438 are compressed radially inwardly and confined within conduitdelivery tube 440, which c,oaxially surrounds conduit 430. Indeed,conduit 430 may be somewhat circumferentially compressed by tube 440.

The portion of assembly 440 at which the proximal end of conduit 430 islocated is shown in FIG. 17. There it will be seen how flaps 438 areconfined within conduit delivery tube 440. FIG. 17 also shows how tubes410, 420, and 440 extend proximally (to the right as viewed in FIG. 17)from the proximal end of conduit 430 so that the physician can remotelycontrol the distal portion of assembly 400 from outside the patient.

To install artificial graft conduit 430 in the patient between regions24 and 34, assembly 400 is fed into the patient along wire 150 throughcatheter 210. When tip 412 reaches coronary artery portion 24, tip 412is threaded into and through the coronary artery wall by rotating tube410 and therefore tip 412. (Tube 120 may be pulled back slightly at thistime to make sure that it does not obstruct tip 412.) The passage of tip412 through the coronary artery wall opens up the aperture in that wall.After tip 412 passes through thIe artery wall, that wall seals itselfagainst the outside of the distal portion of conduit delivery tube 440Das shown in FIG. 18.

The next step is to push tube 410 and tip 412 distally relative todelivery tube 440, which is held stationary. Conduit 430 is initiallymoved distally with components 410 and 412. This may be done byinflating balloon 422 so that it engages conduit 430, and then movingtube 420 distally with components 410 and 412. Distal motion of conduit430 moves barbs 436 beyond the distal end of delivery tube 440, therebyallowing the barbs to spring out inside coronary artery 20 as shown inFIG. 19. This prevents the distal end of conduit 430 from being pulledproximally out of the coronary artery. If balloon 422 was inflatedduring this phase of the procedure, it may be deflated before beginningthe next phase.

The next step is to pull delivery tube 440 back slightly so that it iswithdrawn from coronary artery 20. Then tube 420 is moved distally sothat balloon 422 is radially inside the annulus of barbs 436. Balloon442 is then inflated to ensure that barbs 436 are firmly set in coronaryartery 20. Conditions are now as shown in FIG. 20. Cross sections ofballoon 422 may be L-shaped when inflated (one leg of the L extendingparallel to the longitudinal axis of conduit 430, and the other leg ofthe L extending radially outward from that longitudinal axis immediatelydistal of barbs 436). This may further help to ensure that barbs 436fully engage the wall of coronary artery 20.

The next step is to deflate balloon 422. Then delivery tube 440 iswithdrawn proximally until flap 438a (but not flap 438b) is distal ofthe distal end of the delivery tube. This allows flap 438a to springradially out as shown in FIG. 21. Tube 420 is then withdrawn untilballoon 422 is just distal of flap 438a. Then balloon 422 is inflated,producing the condition shown in FIG. 21.

The next steps are (1) to deflate distal balloon 214, (2) to proximallywithdraw catheter 210 a short way, (3) tD proximally withdraw tube 420to press flap 438a against the outer surface of the aorta wall, and (4)to proximally withdraw delivery tube 440 by the amount required to allowflap 438b to spring out against the interior of catheter 210, all asshown in FIG. 22. As a result of the above-described proximal withdrawalof tube 420, the barbs 439 on flap 438a are urged to enter the aortawall tissue to help maintain engagement between flap 438a and the wallof the aorta. Inflated balloon 422 helps to set barbs 439 in the tissuewhen tube 420 is tugged proximally.

The next step is to insert the distal portion of delivery tube 440 intothe proximal end of conduit 430 as shown in FIG. 22a. The distal end ofconduit 430 may be inserted all the way to the proximal end of balloon422 (see FIG. 23 for a depiction of this). A purpose of this step is tosubsequently help control the rate at which blood is allowed to begin toflow through conduit 430.

The next step is to proximally withdraw catheter 210 by the amountrequired to release flap 438b to spring out against the interior of thewall of aorta 30 as shown in FIG. 22b. Catheter 210 may be subsequentlypushed back against flap 438b as shown in FIG. 23 to help securelyengage that flap against the aorta wall.

Artificial graft conduit 430 is now fully established between aortaregion 34 and coronary artery region 24. The next steps are therefore todeflate balloon 422 and proximally withdraw tube 420, to collapse tip412 and proximally withdraw tube 410, and to proximally withdrawdelivery tube 440. The proximal end of conduit 430 is now as shown inFIG. 24. As possible alternatives to what is shown in FIG. 24, thedistal end of catheter 210 could be left pressed up against proximalflap 438b and/or the distal portion of delivery tube 440 could be leftinside the proximal portion of conduit 430. If the latter possibility isemployed, then delivery of the natural graft conduit (described below)can be through tube 440.

Several illustrative embodiments of collapsible tips 412 are shown inFIGS. 15a-15g. In the first embodiment (shown in FIGS. 15a-15c) a frameof wire struts 412a extends radially out and proximally back from thedistal end of hypotube 410 (see especially FIG. 15a). This frame iscovered with a somewhat elastic polymer cover 412b (FIG. 15b) which isprovided with threads as indicated at 412c. For example, threads 412cmay be made of one or more spirals of nitinol wire or other metal. Whenit is desired to collapse tip 412, another hypotube 410a (which isdisposed around hypotube 410) is shifted distally relative to hypotube410 to invert and collapse tip 412 as shown in FIG. 15c.

In the alternative embodiment shown in FIGS. 15d and 15e, tip 412 has acentral main portion 412e attached to hypotube 410. Around the proximalportion of main portion 412e are a plurality of triangular shapedportions 412f, each of which is connected to main portion 412e by ahinge 412g. The outer surface of the tip is threaded as indicated at412h. For example, in this embodiment tip 412 may be made of a plasticpolymer material, and hinges 412g may be so-called "living" hingesbetween the various masses of the polymer. As soon as triangularportions 412f meet any resistance as tip 412 is withdrawn proximally,they pivot about their hinges 412g to the positions shown in FIG. 15e,thereby greatly reducing the circumferential size of the tip.

In the further alternative embodiment shown in FIGS. 15f and 15g, metalstruts 412j are attached to the distal end of hypotube 410 so that theyextend radially out and proximally back. Although not shown in FIGS. 15fand 15g, struts 412j are covered with a cover and thread, like the cover412b and threads 412c shown in FIG. 15b and described above. A wire 412kconnects a proximal portion of each strut 412j, through an aperture inhypotube 410, to the distal end of another hypotube 410b which isdisposed inside hypotube 410. When wires 412k are relaxed as shown inFIG. 15f, struts 412j extend radially out beyond the circumference ofdelivery tube 440. When it is desired to collapse tip 412, hypotube 410bis pulled back proximally relative to hypotube 410 as shown in FIG. 15g.This causes wires 412k to pull struts 412j in so that the outercircumference of tip 412 is much smaller than the circumference ofdelivery tube 440.

Again, it should be mentioned that the use of a threaded, collapsibletip 412 as described above is only one of several possibilities. Otheralternatives are discussed below after completion of the discussion ofthe illustrative procedure which is being described and which will nowbe further considered with reference to FIG. 25 and subsequent FIGS.

As has been mentioned, the illustrative procedure being describedassumes that natural body conduit (e.g. a Length of the patient'ssaphenous vein that has been harvested for this purpose) is installedinside artificial conduit 430 after installation of the latter conduit.An illustrative assembly 500 for delivering a length of natural bodyconduit to installed conduit 430 is shown in FIG. 25.

As shown in FIG. 25, assembly 500 includes a tube 510 disposed aroundwire 150 so that tube 510 is freely movable in either direction alongwire 150. Tube 510 has an inflatable annular balloon 512a near itsdistal end and another inflatable annular balloon 512b spaced in theproximal direction from balloon 512a. Tube 510 includes separateinflation lumens (not shown) for each of balloons 512 so that theballoons can be separately inflated and deflated. An annular collarstructure or ring 520a is disposed concentrically around balloon 512a,and a similar annular collar structure or ring 520b is disposedconcentrically around balloon 512b. Balloons 512 may be partly inflated.Each of rings 520 may have radially outwardly extending barbs 522. Alength of natural body conduit 530 (e.g., saphenous vein as mentionedearlier) extends from ring 520a to ring 520b around the interveningportion of tube 510. Barbs 522 may extend through the portions ofconduit 530 that axially overlap rings 520. A delivery tube 540 isdisposed around conduit 530. In use, tubes 510 and 540 extend proximally(to the right as viewed in FIG. 25) out of the patient to permit thephysician to remotely control the distal portion of assembly 500.

Although not shown in FIG. 25, assembly 500 may include a spring coil(similar to coil 450 in FIG. 36) extending between rings 520 inside ofconduit 530 to help hold conduit 530 open and out against delivery tube54) or subsequently out against conduit 430. Instead of balloons 512being both in the same tube 510, balloon 512a may be on a relativelysmall first tube, while balloon 512b is on a larger second tube thatconcentrically surrounds the proximal portion of the first tube. Thefirst and second tubes are axially movable relative to one another,thereby allowing the distance between balloons 512 to be adjusted forgrafts 530 of different lengths.

Assembly 500 is employed by placing it on wire 150 leading into catheter210. Assembly 500 is then advanced distally along wire 150 throughcatheter 210 and then into conduit 430 until the distal end of conduit530 is adjacent the distal end of conduit 430 and the proximal end ofconduit 530 is adjacent the proximal end of conduit 430. The conditionof the apparatus at the distal end of assembly 500 is row as shown inFIG. 26. The condition of the apparatus at the proximal end of conduit530 is as shown in FIG. 28.

The next step is to proximally withdraw delivery tube 540 so that thedistal portion of conduit 530 and distal barbed ring 520a are no longerinside the distal portion of delivery tube 540. Then distal balloon 512ais inflated to circumferentially expand ring 520a and to set barbs 522through conduit 530 into the surrounding portion of conduit 430 andcoronary artery wall portion 24. This provides a completed anastomosisof the distal end of conduit 530 to coronary artery 20. FIG. 27 showsthe condition of the apparatus at this stage in the procedure.

The next step is to continue to proximally withdraw delivery tube 540until the proximal end of conduit 530 and proximal ring 520b are nolonger inside tube 540 (see FIG. 29). Then proximal balloon 512b isinflated to circumferentially expand ring 520b and thereby set barbs 522through conduit 530 into the surrounding portion of conduit 430 andaorta wall portion 34 (see FIG. 30). This provides a completedanastomosis of the proximal end of conduit 530 to aorta 30.

The next step is to deflate balloons 512a and 512b and proximallywithdraw tube 510 and delivery tube 540 from the patient via catheter210. Then wire 150 is withdrawn from the patient, either by pulling itproximally from catheter 210 or by pulling it proximally from elements110 and 120. Lastly, elements 110, 120, and 210 are all proximallywithdrawn from the patient to conclude the procedure. The bypass that isleft in the patient is as shown in FIG. 31. This bypass extends fromaorta 30 at location 34 to coronary artery 20 at location 24. The bypassincludes natural body conduit 530 inside artificial graft conduit 430.One end of the bypass is anchored and anastomosed to coronary artery 20by barbs 436 and ring 520a. The Dther end of the bypass is anchored andanastomosed to aDrta 30 by flaps 438 and ring 520b.

The particular uses of the invention that have been described in detailabove are only illustrative of many possible uses of the invention.Other examples include same-vessel bypasses in the coronary area andvessel-to-vessel and same-vessel bypasses in other portions of thecirculatory system (including neurological areas, renal areas,urological areas, gynecological areas, and peripheral areas generally).A same-vessel bypass is a bypass that extends from one portion of avessel to another axially spaced portion of the same vessel. In FIG. 32,bypass 620 is a same-vessel bypass around a narrowing 612 in vessel 610.For ease of comparison to previously described embodiments, the variouscomponents of bypass 620 are identified using the same reference numbersthat are used for similar elements in FIG. 31. The invention is alsoapplicable to procedures similar to any of those mentioned above, butfor non-circulatory systems such as urological tubing.

It has been mentioned that the collapsible tip structures shown, forexample, in FIGS. 15-15g are illustrative of only one of severalpossible approaches to providing a structure that can penetrate the wallof coronary artery 20 from outside the artery. Another example of asuitable structure is shown in FIG. 33. To facilitate comparison to FIG.15, FIG. 33 uses reference numbers with primes for elements that aregenerally similar to elements identified by the corresponding unprimedreference numbers in FIG. 15.

In the embodiment shown in FIG. 33 distal tip 412' has external threads414 for helping to grip and dilate tissue such as the wall of coronaryartery 20 as tip 412' is rotated about wire 150 by rotation ofproximally extending tubular shaft 410'. Threads 414 continue as threads442 on the exterior of the distal portion of tube 440'. Threads 414 alsothreadedly engage with threads 444 on the interior of the distal portionof tube 440'. Thus when both of structures 410' and 440' are rotatedtogether, threads 414 and 442 tend to pull tip 412' and then the distalportion of tube 440' into and through the wall of coronary artery 20. Inthe course of this, threads 412' transfer the tissue to threads 442.Thereafter, structure 410' can be removed from structure 440' byrotating structure 410' in the direction relative to structure 440' thatcauses threads 414 and 444 to cooperate to shift tip 412' proximallyrelative to structure 440'. When tip 412' has thus shifted proximallybeyond threads 444, elements 410' and 412' can be pulled proximally outof the patient. Tube 440', which remains in place through the coronaryartery wall, can thereafter be used as a guide tube for delivery of agraft structure (such as 430 (FIGS. 15-17)) and associatedinstrumentation (such as structure 420 (e.g., FIGS. 15 and 17)) to theoperative site.

Another illustrative alternative embodiment of some of theinstrumentation shown in FIG. 15 is shown in FIGS. 34 and 35. Onceagain, to facilitate comparison to FIG. 15, FIGS. 34 and 35 usereference numbers with primes for elements that are generally similar toelements identified by the corresponding unprimed reference numbers inFIG. 15. In the embodiment shown in FIGS. 34 and 35 barbs 436' areconnected to the distal end of a serpentine ring 439 which is connectedin turn to the distal end of frame 432'. Barbs 436' are initially heldin the form of a distally pointed cone by yieldable bands 437a, 437b,437c, and 437d. As elsewhere along graft conduit 430', the spacesbetween barbs 436' are substantially filled by a highly elastic materialsuch as silicone rubber. Bands 437 may be made of a polymeric or othersuitable yieldable material. Alternatively, bands 437 could beserpentine metal members that yield by becoming straighter. Bards 437are initially strong enough to prevent barbs 436' from flaring radiallyoutward from conduit 430' as the barbs are resiliently biased to do.However, bands 437 can be made to yield by inflating balloon 422' (onthe distal end of tube 420') inside the annulus of barbs 436'.

Barbs 436' can be forced through tissue such as the wall of coronaryartery 20 in their initial cone shape. Sufficient pushing force can beapplied to the cone of barbs 436' in any of several ways. For example,tube 420' may be metal (e.g., stainless steel) hypotube which cantransmit pushing force to the cone of barbs 436' by inflating balloon422' to trap the base of the cone between balloon 422' and tube 440.Additional pushinag force may then also be applied via tube 440 itself.

When a sufficient portion of the height of the cone of barbs 436' isthrough the coronary artery wall, balloon 422' is inflated inside thecone as shown in FIG. 35 to cause bands 437 to yield. This allows barbs436' to flare radially outward inside the coronary artery, therebyanchoring the distal end of conduit 430' to the artery. Bands 437 may bemade progressively weaker in the distal direction to facilitate promptyielding of distal bands such as 437a and 437b in response to relativelylittle inflation of balloon 422', whereas more proximal bands such as437c and 437d do not yield until somewhat later in response to greaterinflation of balloon 422'. This progression of yielding may help ensurethat the annulus of barbs flares out in the desired trumpet-bell shapeinside the coronary artery.

FIGS. 36 and 37 illustrate another possible use of a cone structure likethat shown in FIGS. 34 and 35, as well as illustrating other possibleaspects of the invention. These FIGS. illustrate a structure that can beused to deliver an artificial graft conduit, or a natural graft conduit,or both an artificial graft conduit and a natural graft conduitsimultaneously (e.g., with the natural conduit coaxially inside theartificial conduit). In the particular case shown in FIGS. 36 and 37 itis assumed that only natural graft conduit is being delivered, but itwill be readily apparent that artificial graft conduit could besubstituted for or added outside the natural graft conduit.

In the embodiment shown in FIGS. 36 and 37 the cone of barbs 436' ismounted on the distal end of a highly elastic coil spring 450. Theproximal end of coil 450 is attached to ring 460. The cone of barbs 436'is provided with additional, relatively short, radially outwardlyprojecting barbs 436" near the proximal base of the cone. As shown inFIG. 37, barbs 436" extend into and/or through the distal portion of alength of graft tubing 530, which (as has been mentioned) is assumed inthis case to be natural body organ tubing such as saphenous vein. Ring460 is similarly provided with radially outwardly extending barbs 462which extend into and/or through the proximal portion of graft conduit530. Ring 460 also includes resilient radially outwardly extendingannular flaps 438a and 438b with barbs 439, all similar tocorrespondingly numbered elements in FIG. 16. Spring 450, which isinside conduit 530 between the cone of barbs 436' and ring 460, helps tosupport and hold open the graft conduit. Structure 420' (similar tostructure 420' in FIGS. 34 and 35 and including balloon 422' as shown inthose FIGS.) is disposed around wire 150 inside structures 436', 450,460, and 530. Delivery tube 440 is disposed around conduit 530.

The embodiment shown in FIGS. 36 and 37 illustrates a structure whichcan be used to deliver and install natural body organ conduit withoutany full length artificial graft conduit being used. In a manner similarto what is shown in FIGS. 34 and 35, the structure shown in FIG. 37 isdelivered to the operative site via wire 150. The cone of barbs 436' isforced through the wall of coronary artery 20 and then flared radiallyoutward inside the coronary artery to anchor the distal end of the graftconduit to that artery. The distal end of delivery tube 440 is pulledback as needed to aid in attachment of the distal end of the graftstructure. Attachment of the proximal end of the graft structure to thewall of aorta 30 is performed similarly to what is shown in FIGS. 21-24.Accordingly, with distal flap 438a just outside the wall of aorta 30,delivery tube 440 is pulled back proximally to expose that flap. Flap438a is thereby released to spring out and engage the outer surface ofthe aorta wall. After that has occurred, proximal flap 438b is adjacentthe inner surface of the aorta wall. Tube 440 is pulled back proximallyeven farther to expose flap 438b so that it can spring out and engagethe inner surface of the aorta wall. Natural body organ graft 530 is nowfully installed in the patient. Structures 436', 450, and 460 remain inplace in the patient to help anchor the ends of graft conduit 530 and tohelp hold open the medial portion of that conduit.

In embodiments like FIGS. 36 and 37, coil 450 is optional. If coil 450is used, its ends may or may not be attached to structures 436 and/or460.

A coil like coil 450 can be used in other embodiments of the invention.For example, a coil like 450 could be used between rings 520a and 520bin embodiments like that shown in FIG. 25 to help hold open graftconduit 530 in that embodiment.

Still another illustrative alternative embodiment of some of theinstrumentation shown in FIG. 15 is shown in FIG. 38. To facilitatecomparison to FIG. 15, FIG. 38 uses reference numbers with double primesfor elements that are generally similar to elements identified by thecorresponding unprimed reference numbers in FIG. 15. In the embodimentshown in FIG. 38, the distal end of artificial graft conduit 430" isattached to expandable ring 430a. Elongated barbs 436" extend distallyfrom the distal end of ring 430a. The distal ends of barbs 436" areturned back in the proximal direction and extend just far enough intothe distal end of tube 420" to be releasably retained by that tube.Barbs 436" are resiliently biased to extend radially outward from ring430a, but are initially restrained from doing so by the presence oftheir distal end portions in the distal end of tube 420". Thus barbs436" initially form a distally pointing cone that can be pushed throughtissue such as the wall of coronary artery 20 in the same manner thathas been described above in connection with FIGS. 34-37. Structure 420",which may be metal (e.g., stainless steel) hypotube with an inflatableannular balloon 422" near its distal end, may be used to help push thecone through the tissue.

After the distal portion of the cone of barbs 436" has been pushedthrough the wall of coronary artery 20, tube 420" is shifted proximallyrelative to the barbs to release the distal end portions of the barbs.This allows barbs 436" to spring radially outward from ring 430a insidecoronary artery 20, thereby anchorirg the distal end of the graftconduit in the coronary artery. Ring 430a can then be circumferentiallyexpanded to increase the size of the connection between coronary artery20 and the distal portion of the graft conduit. If desired, each ofbarbs 436" may he twisted 180° as shown in FIG. 39 before it enters thedistal end of tube 420". This promotes turning of the extreme distal endportions of the barbs toward the coronary artery wall when the barbs arereleased from tube 420".

Ring 430a and barbs 436" may be made of any suitable material such asany 300-series stainless steel (e.g., 316L stainless steel). Anothermaterial that may be suitable for barbs 436" is nitinol. As inpreviously described embodiments, the elastic cover 434 that forms partof conduit 430" preferably extends to regions 430a and 436".

A preferred artificial graft (such as conduit 430 in FIG. 16) inaccordance with this invention includes an open frame structure (such as432 in FIG. 16). This frame structure may have any desired shape such asa tube, a flat or contoured sheet, etc. The frame structure may beformed in any suitable way such as by cutting apertures in an initiallyimperforate structure; forming a mesh of strands of frame material;braiding, knitting, weaving, or felting together strands of framematerial; etc. The frame material is preferably an elastic material.Preferred materials are metal, although polymeric materials may also beused. The presently most preferred material is nitinol, and thepresently most preferred structure for the frame of a tubular graft is abraid of nitinol wires.

The above-described graft frame is preferably covered with a covering ofelastic rubber-like material which substantially fills the apertures inthe frame as at 434 in FIG. 16. The covering may be inside the framestructure, outside the frame structure, or both inside and outside theframe structure. Preferred rubber-like materials for the covering arepolymeric materials, especially polymeric rubber materials. Thepresently most preferred rubber-like material is silicone. Examples ofother suitable rubber-like materials are stretchable urethane,stretchable PTFE, natural rubber, and the like. For some applications itmay be desirable to make the covering porous. Other applications may notbenefit from such porosity. Thus the covering can be made either porousor non-porous as desired.

The graft structure may include one or more coatings over theabove-described covering. In the case of a tubular graft the coating(s)may be inside the tube, outside the tube, or both inside and outside thetube. Possible coating materials include bio-compatible materials and/ordrugs. Examples include hydrophylic polymers such as hydrophylicpolyurethane (to create a lubricious surface), parylene (a polymercommonly used to coat pacemakers), PTFE (which may be deposited from aPTFE vapor using a process that is sometimes called vapor transport),the drug Heparin (a common anti-coagulant), collagen, human cellseeding, etc. One purpose of such a coating may be to give the coatedsurface a very high degree of bio-compatibility and/or a very hicghdegree of smoothness.

The graft structure may or not include hooks, barbs, flaps, or othersimilar structures for such purposes as helping to anchor the graft inthe body, provide anastomoses between the graft and existing bodytubing, etc. Several examples of such structures are shown and describedelsewhere in this specification. If provided, such hooks, barbs, flaps,and the like may be extensions of the frame structure or may be moldedwith or otherwise added to the frame or covering.

The most preferred grafts of this invention (e.g., those with a nitinolframe and silicone covering) are highly elastic. The elastic nature ofthese graft structures allows them to be deployed less invasively (e.g.,intravascularly or at least percutaneously). This avoids or reduces theneed for surgical implantation. For example, a tubular graft of thisconstruction can be stretched to several times its relaxed length, whichgreatly reduces its diameter. This facilitates intravascular delivery ofthe graft. When released from the delivery apparatus, the graftautomatically returns to its relaxed length and diameter, with noill-effects of any kind from its previous deformation. If installed inthe circulatory system, the graft is so flexible and elastic that itpulsates in response to pressure waves or pulses in the blood flow. Thisdistensibility of the graft may help prevent blood clots. Coatings thatare used on the graft are preferably similarly distensible.

In the grafts of this invention that are made with a braided nitinolwire frame and a silicone covering, the preferred wire diameter is inthe range from about 0.0005 to about 0.01 inches. An especiallypreferred wire diameter is about 0.002 inches. The preferred silicorecovering thickness is in the range from about 0.00025 to about 0.1inches. Two covering layers may be used: one inside and one outside theframe structure. If the covering is made porous, the preferred pore sizeis in the range from about 1 to about 500 microns. An especiallypreferred pore size is about 30 microns. The preferred covering porosityis in the range from about 50% to about 95%. In other words, from about50% to about 95% of the volume of the covering is pore space. If anycoatings are applied to the graft, they are preferably thinner than thecovering.

For the preferred grafts of this invention, a preferred manufacturingprocess in accordance with the invention includes placing or forming theframe structure of the graft on a form (e.g., a rod-like mandrel or tubein the case of the frame for a tubular graft). The form (e.g., mandrel)may be coated with a release agent such as polyvinyl alcohol. Thecovering is then applied to the frame or the form. The covering iscured, and the frame and covering are removed from the form. Any releaseagent that remains on the graft is removed. For example, if the releaseagent is polyvinyl alcohol, it may be removed by boiling the graft inwater. If a covering is desired on the inside of the graft, a layer ofthe covering material may be applied to the form before the framestructure is placed or formed on the form. The form may be provided witha very smooth surface to give the finished graft a correspondinglysmooth surface. For example, a very smooth mandrel may be used to givethe inside of a tubular graft a very smooth surface.

If one or more coatings are desired on the graft, the coating may bedone at any suitable time. For example, the coating may be done afterthe graft has been removed from the form. The coating or coatings may beapplied using any suitable technique such as dipping, electrostaticspraying, vapor transport, in vitro cell reproduction, etc.

A preferred method in accordance with the invention for making the graftcovering porous is to mix particles of another material with thecovering material before applying the covering material to the frame.The particulate material is selected as one which is stable or at leastrelatively stable during curing of the covering on the frame, but whichcan then be removed from the cured covering to leave the covering withthe desired porosity. For example, the particulate material may be asalt such as ammonium carbonate, which is relatively stable attemperatures substantially below about 78° C., but which vaporizesrelatively rapidly at an elevated temperature (i.e., about 78° C.) thatis not harmful to the cured coating material. Any other particulatematerial that can be removed by vaporization or solution can be used.For example, the particulate material may be removed by dissolving inwater or another solvent, by exposure to air or another vaporizationmedium, by heat, by vacuum, or by any other suitable means.

Porosity of the covering is believed to be beneficial for circulatorysystem grafts. It may promote growth of a cell structure on the insidewall of the graft. And in all uses, porosity may promote betteradherence of the above-mentioned coatings to the graft.

It will be understood that the foregoing is only illustrative of theprinciples of the invention, and that various modifications can be madeby those skilled in the art without departing from the scope and spiritof the invention. For example, the order of some steps in the proceduresthat have been described are not critical and can be changed if desired.The manner in which radiologic elements and techniques are used forobservation of the apparatus inside the patient may vary. For example,radiologic fluids may be injected into the patient through variouslumens in the apparatus to help monitor the location of variousapparatus components in the patient, and/or radiologic markers (of whichthe above-described markers such as 112, 124, and 154 are examples) maybe provided anywhere on the apparatus that may be helpful to thephysician.

The invention claimed is:
 1. The method for forming a tubular graftconnection between first and second sections of a patient's existingtubular body organ structure comprising the steps of:passing a length ofgraft tubing axially along an interior lumen of a portion of saidexisting structure to place a first end portion of said length of qrafttubing inside said first section of said existing structure; causingsaid first end portion of said length of graft tubing to emerge frominside to outside of said first section of said existing structure viaan aperture in a wall of said first section; extending said first endportion of said length of graft tubing outside of said existingstructure to an aperture in a wall of said second section of saidexisting structure; securing said first end portion of said length ofgraft tubing to said second section of said existing structure; andsecuring a portion of said length of graft tubing which is axiallyspaced from said first end portion to said first section of saidexisting structure.
 2. The method defined in claim 1 wherein each ofsaid steps is at least partly controlled from outside of the patient viainstrumentation that passes through said existing structure to reach atleast one of said first and second sections.
 3. The method defined inclaim 1 wherein said step of securing said first end portion of saidlength of graft tubing comprises the step of:forming an anastomosisbetween said first end portion of said length of graft tubing and saidsecond section of said existing structure.
 4. The method defined inclaim 1 wherein said step of securing a portion of said length of grafttubing which is axially spaced from said first end portion comprises thestep of:forming an anastomosis between said portion which is axiallyspaced and said first section of said existing structure.
 5. The methoddefined in claim 1 wherein said length of graft tubing includesartificial graft tubing.
 6. The method defined in claim 1 furthercomprising the step of:removing a length of the patient's natural bodyorgan tubing for use as at least part of the length of graft tubing. 7.The method defined in claim 6 further comprising the step of:disposingthe natural body organ tubing substantially coaxially inside artificialgraft tubing to provide said length of graft tubing.
 8. The methoddefined in claim 1 wherein said steps of passing, causing, and extendingare preceded by the step of:positioning a longitudinal structure alongthe interior lumen of said portion of said existing structure and out ofsaid existing structure via said aperture in said first section to saidaperture in said second section.
 9. The method defined in claim 8wherein said steps of passing, causing, and extending are at leastpartly performed by moving said length of graft tubing along saidlongitudinal structure.
 10. The method defined in claim 9 wherein saidlength of graft tubing is placed coaxially around said longitudinalstructure in order to move said length of graft tubing along saidlongitudinal structure.
 11. The method defined in claim 8 wherein saidpositioning step comprises the steps of:passing a first length of thelongitudinal structure along the interior lumen of said portion of saidexisting structure so that a distal portion of said first length extendsout from said existing structure via said aperture in said firstsection; passing a second length of longitudinal structure along theinterior lumen of a part of said existing structure which is at leastpartly different from said portion of said existing structure so that adistal portion of said second length extends out from said existingstructure via said aperture in said second section; and interengagingsaid distal portion of said first length and said dislal portion of saidsecond length at an interengagement location which is between saidaperture in said first section and said aperture in said second sectionand outside of said existing structure.
 12. The method in claim 11wherein said positioning step further comprises the step of:afterperforming said interengaging step, axially shifting the interengagingfirst and second lengths so that the interengagement location is nolonger between said aperture in said first section and said aperture insaid second section outside of said existing structure.
 13. The methoddefined in claim 12 wherein said axially shifting is performed untilsaid interengagement location is outside of the patient.
 14. The methoddefined in claim 1 wherein said steps of passing and causing arepreceded by the step of:positioning a tubular instrument along theinterior lumen of said portion of said existing structure and out ofsaid existing structure via said aperture in said first section.
 15. Themethod defined in claim 14 wherein said steps of passing, causing, andextending are at least partly performed by moving said length of drafttubing through said tubular instrument.
 16. The method defined in claim1 wherein said length of graft tubing is disposed in a delivery tubeinstrument during said passing, causing, and extending steps, andwherein said method further comprises the step of removing said deliverytube instrument from said length of graft tubing prior to completion ofsaid securing steps.
 17. The method defined in claim 1 wherein saidlength of graft tubing includes selectively operable fasteners, andwherein said step of securing said first end portion comprises the stepof:operating fasteners adjacent to said second section to fasten saidfirst end portion to said second section.
 18. The method defined inclaim 17 wherein said operating step causes said fasteners adjacent tosaid second section to extend radially outward from said length of grafttubing into said second section.
 19. The method defined in claim 17wherein said fasteners adjacent to said second section are disposed inan annular array which is substantially concentric with said length ofgraft tubing, and wherein said operating step comprises the stepof:circumferentially expanding said annular array into engagement withsaid second section.
 20. The method defined in claim 17 wherein saidoperating step comprises the steps of:disposing an inflatable memberinside said length of graft tubing adjacent to said fasteners adjacentto said second section; and inflating said inflatable member to helpsaid fasteners securely engage said second section.
 21. The methoddefined in claim 20 wherein said operating step further comprises thestep of:deflating said inflatable member after performing said inflatingstep.
 22. The method defined in claim 1 wherein said length of grafttubing includes selectively operable fasteners, and wherein said step ofsecuring a portion of said length of graft tubing to said first sectioncomprises the step of:operating fasteners adjacent to said first sectionto fasten said portion of said length of graft tubing which is axiallyspaced from said first end portion to said first section.
 23. The methoddefined in claim 22 wherein said operating step causes said fastenersadjacent to said first section to extend radially outward from saidlength of graft tubing into said first section.
 24. The method definedin claim 22 wherein said fasteners adjacent to said first section aredisposed in an annular array which is substantially concentric with saidlength of graft tubing, and wherein said operating step comprises thestep of:circumferentially expanding said annular array into engagementwith said first section.
 25. The method defined in claim 22 wherein saidoperating step comprises the steps of:disposing an inflatable memberinside of said length of graft tubing adjacent to said fastenersadjacent to said first section; and inflating said inflatable member tohelp said fasteners securely engage said first section.
 26. The methoddefined in claim 25 wherein said operating step further comprises thestep of:deflating said inflatable member after performing said inflatingstep.
 27. A method of providing a tubular graft connection between firstand second tubular bode organ sections in a patient comprising the stepsof:inserting a first elongated instrument substantially coaxially intosaid first tubular body organ section; inserting a second elongatedinstrument substantially coaxially into said second tubular body organsection; extending a first longitudinal structure from said firstinstrument so that a distal portion of said first structure passesthrough a wall of said first tubular body organ section; extending asecond longitudinal structure from said second instrument so that adistal portion of said second structure passes through a wall of saidsecond tubular body organ section; interengaging said distal portions ofsaid first and second structures outside of said first and secondtubular body organ sections; and extending a length of graft tubingalong at least one of said first and second structures so that saidlength of graft tubing extends between said first and second body organsections outside of said first and second body organ sections.
 28. Themethod defined in claim 27 wherein said interengaging step takes placeinside the body of the patient, and wherein said length of graft tubingextends between said first and second body organ sections outside ofsaid first and second body organ sections but inside the body of thepatient as a result of performing said step of extending a length ofgraft tubing.
 29. The method defined in claim 27 wherein all of saidextending and interengaging steps are performed inside the body of thepatient under remote control from outside the patient via at least oneof said first and second instruments.
 30. The method defined in claim 27further comprising the step of:after performing said interengaging step,longitudinally displacing the interengaged first and second structuresso that said one of said first and second structures extendscontinuously between said first and second tubular body organ sectionsoutside of said first and second tubular body organ sections.
 31. Themethod defined in claim 27 further comprising the step of:afterperforming said step of extending said length of graft tubing, securingeach end of said length of graft tubing to a respective one of saidfirst and second tubular body organ sections so that said length ofgraft tubing opens into both of said first and second tubular body organsections.
 32. The method defined in claim 27 further comprising the stepof:after performing said step of extending said length of graft tubing,longitudinally withdrawing from the patient any of said first and secondstructures that remain in the patient.
 33. The method defined in claim32 further comprising the step of:after performing said longitudinallywithdrawing step, removing said first and second instruments from thepatient.
 34. The method defined in claim 27 further comprising the stepof:removing from the patient body organ tubing for use in said length ofgraft tubing.
 35. The method defined in claim 27 wherein said length ofgraft tubing comprises an artificial graft.
 36. The method defined inclaim 35 further comprising the step of:disposing natural body organtubing coaxially inside of said artificial graft.
 37. The method definedin claim 36 wherein said step of extending a length of graft tubingcomprises the steps of:extending said artificial graft along at leastone of said first and second structures so that said artificial graftextends between said first and second body organ sections outside ofsaid first and second body organ sections; and extending said naturalbody organ tubing along at least one of said first and second structuresso that said natural body organ tubing extends between said first andsecond body organ sections inside of said artificial graft.
 38. Themethod defined in claim 35 further comp rising the step of:afterperforming said step of extending said artificial graft, securing eachend of said artificial graft to a respective one of said first andsecond tubular stody organ sections so that said artificial graft opensinto both of said first and second tubular body organ sections.
 39. Themethod defined in claim 38 further comprising the step of:afterperforming said step of extending said natural body organ tubing,securing each end of said natural body organ tubing to a respective oneof said first and second tubular body organ sections so that saidnatural body organ tubing opens into both of said first and secondtubular body organ sections.
 40. The method defined in claim 27 whereinthe distal portion of one of said first and second structures has aselectively closable snare for engaging the distal portion of the otherof said first and second structures when the snare is closed on thedistal portion of said other structure, and wherein said interengagingstep comprises the steps of:positioning the distal portions of saidfirst and second structures relative to one another so that said snarecan engage the distal portion of said other structure; and closing saidsnare.